Comparing with conventional secondary batteries such as lead-acid batteries, nickel-metal hydride batteries and the like, the Li-ion battery has advantages like high energy density, high output voltage, low self-discharge, no memory effect and environment friendliness, which therefore is widely applied and developed. The property of the key material of the power and energy storage Li-ion battery is the dominating factor of the performance of the battery, and the research on the cathode material has always been a hot spot for scientists. Cathode materials like LiCoO2, LiMnO4, LiFePO4 and LiNixCoyMn1-x-yO2 have been widely researched. However, the Li-ion battery system assembled by these materials has defects like low specific energy density, high cost and poor safety performance, which cannot satisfy the requirements of electric vehicles on energy storage batteries.
The cathode material of spinel type lithium-manganese-nickel-containing composite oxide is always the research hotspot of the cathode materials for the Li-ion battery due to its advantages of excellent rate performance, high working voltage, low cost and the like. However, the disadvantages of the cathode material of spinel type lithium-manganese-nickel-containing composite oxide like unstable surface structure and dissolution of manganese metal during cycling seriously limit its large-scale application.
In order to develop cathode material of spinel type lithium-manganese-nickel-containing composite oxide with excellent performance which meets the requirements of electric vehicles on rate performance of the battery, researchers have developed a variety of technical means to modify and improve the cathode material for spinel type lithium-manganese-nickel-containing composite oxide. The prior art discloses a modification method of the cathode material of spinel type lithium-manganese-nickel-containing composite oxide used for the Li-ion battery, which obtains the lithium-nickel-manganese oxide material coated with aluminum hydroxide mainly through liquid-phase coating, and then obtains the cathode material of lithium-nickel-manganese oxide coated and modified by alumina through hot processing in a muffle furnace at 300˜450° C.; The performance of the modified cathode material of spinel type lithium-manganese-nickel-containing composite oxide was improved for about 10% compared with the uncoated material.
The prior art also discloses a method combining the sol-gel method and the solid phase method, so as to obtain uniform distribution of Li2TiO3 coated on the LiNi0.5Mn1.5O4 material and good uniformity of the finally prepared cathode material, so that the prepared cathode material has good cycle performance and rate performance It is also disclosed to add the microwave sensitive material of zirconia in the preparing process of the precursor, so that the reaction materials can effectively absorb microwaves and be quickly heated up to the reaction temperature of 700˜950° C., so as to significantly shorten the microwave sintering time to 1˜10 minutes; at the same time when the lithium-nickel-manganese oxide material is sintered at high temperature, zirconia and the Li source react and generate a coating layer of lithium ion conductor Li2ZrO3 on the surface of lithium-nickel-manganese oxide, which significantly improves the cycle performance and rate performance of the product.
Simple solid state reaction has great difficulties in forming a dense coating layer on the surface of the cathode material of spinel type lithium-manganese-nickel-containing composite oxide, and the 5V spinel type lithium-manganese-nickel-containing composite oxide system inevitably has some side reactions; in the meantime, the presently used coating materials are all metal oxides or phosphates, these coating materials have low electronic conductivity and lithium ion conductivity coefficient, therefore, it is in an urgent need to find a modification method of the cathode material of spinel type lithium-manganese-nickel-containing composite oxide which can form a dense coating layer on the surface of the spinel type lithium-manganese-nickel-containing composite oxide, and the coating layer has higher electronic conductivity and lithium ion conductivity coefficient, so that the cathode material of spinel type lithium-manganese-nickel-containing composite oxide has higher cycle stability and rate performance.